title: The electrochemical detection of droplets in microfluidic devices.
abstract: This paper presents a new electrochemical method for the detection and characterisation of aqueous droplets in an organic carrier fluid (1,2-dichloroethane) formed in flow-focusing microfluidic devices. The devices consist of a conventional flow-focusing channel 250 microm wide and 250 microm deep cast out of poly(dimethylsiloxane) (PDMS) which is sealed onto a glass substrate containing a set of microelectrodes 100 microm long. Chronoamperometric analysis of a suitable electrolyte contained in the organic phase is presented for characterising the droplet frequency and size. This chronoamperometric method is then extended to a dual working electrode approach in order to determine the velocity of the droplet. Good agreement between experimental measurements and theory was observed.
authors.affiliation: Department of Chemical Engineering, University of Cambridge, Cambridge, UKCB2 3RA.
authors.forename: Shujuan
authors.initials: S
authors.lastname: Liu
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Gu
authors.forename: Rudolph B
authors.initials: RB
authors.lastname: Le Roux
authors.forename: Sinéad M
authors.initials: SM
authors.lastname: Matthews
authors.forename: Daniel
authors.initials: D
authors.lastname: Bratton
authors.forename: Kamran
authors.initials: K
authors.lastname: Yunus
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Fisher
authors.forename: Wilhelm T S
authors.initials: WT
authors.lastname: Huck
mesh_terms: D003365:Costs and Cost Analysis; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004563:Electrochemistry; D004581:Electronics; D005898:Glass / Q000737:chemistry; D008839:Microelectrodes; D044085:Microfluidics / Q000191:economics / Q000379:methods*; D055620:Optical Phenomena
chemical_list: D004129:Dimethylpolysiloxanes; C013830:baysilon